This invention relates to a novel class of triazine-urea compounds useful as organic gellants for grease formulations. More particularly, this invention is directed to certain polyureido-s-triazine derivatives which are quite efficacious as high temperature grease thickening agents and to novel grease compositions gelled therewith.
In modern practice, it has become increasingly important that grease compositions be able to provide adequate lubrication at high temperature, e.g., temperatures of 350.degree. F. to 450.degree. F. or higher. Further, because many of the newer high temperature grease applications, e.g., high speed sealed bearings, require that the grease maintain a high level of lubricant activity for extended time periods, it is also essential that the thickener impart a high degree of mechanical stability on the grease formulation at such high temperatures.
A variety of thickening agents have been proposed for use in such high temperature applications including soap base thickeners, inorganic clay thickeners and organic thickening agents. Of these classes of thickening agents, the organic thickeners, specifically those containing urea or ureido functional groups, have been considered quite attractive because of their ashless nature and high temperature thickening properties. Examples of such organic thickening agents include polyureas and ureido compounds such as those described in U.S. Pat. Nos. 3,242,210, 3,243,372, 3,725,279 and 3,846,314, as well as dibenzimidazole-diureas disclosed in U.S. Pat. No. 3,752,765 and related arylcarbamyl thickeners described in U.S. Pat. No. 3,255,109. These organic thickeners are generally prepared by reacting one or more mono-, di- or polyamines with one or more mono-, di- or polyisocyanates, with the synthesis scheme in the case of the arylcarbamyl compounds involving the reaction of an aromatic amine with the reaction product of an aromatic diisocyanate and p-aminobenzoic acid.
While many of the aforementioned organic grease thickeners possess or retain their gellant properties in conventional mineral or synthetic hydrocarbon lubricant base oils at high temperatures, as shown by the high dropping points of greases formulated therefrom, they do not afford the extended operating lifetimes, as measured by thermal and mechanical stability at high temperatures, desired for sealed mechanical systems where lubricant life is a measure of mechanical life. Consequently, it would be quite desirable if an organic thickening agent could be developed in which high temperature gellant properties are combined with superior thermal and mechanical stability in such high temperature applications.